BENEFICIAL ACTION OF LIME. 91 



destroying the injurious excess of vegetable remains, the 

 farmer will in vain expect a favourable result from the 

 application of lime in the following years, unless the 

 same causes should recur which had originally impaired 

 the fertility of the field. 



In a soil wherein there are putrescent and decaying 

 substances not a single plant will thrive, except mush- 

 rooms ; and it seems that every chemical process going 

 on in the neighbourhood of roots disturbs that of their 

 own. Decaying substances in excess, by generating 

 too much carbonic acid, injure even those plants which 

 thrive particularly well in a humose soil containing a 

 moderate quantity of humus. " x " 



Upon deep-rooting plants, such as turnips, clever, 

 sanfoin, peas and beans, organic matters accumulating 

 largely in the subsoil act very injuriously, especially in 

 clay, where ' they decay much more slowly than in a 

 lime soil. The process of decay is communicated to the 

 sickening roots, in which spores of fungi find a suitable 

 soil for their developement. When turnips are thus 

 affected, they become the prey of certain insects, which 

 deposit their eggs in the roots, causing in their develope- 

 ment a strange alteration and disturbance of the vege- 

 table process ; for in the diseased parts spongy tmuours 

 arise, the inner substance of which becomes soft and 

 emits a bad smell, and in this state serves to nourish 

 the larva of the small fly. 



All these processes, however obscure in themselves, 

 are put an end to by applying lime to such a field ; a 

 proper lime dressing will always attain this object. 

 Fields that are particularly rich in organic remains 



* Gasparini sowed a few grains of spelt in a pot with washed earth 

 from Vesuvius; these produced plants which continued to grow in a 

 healthy state. In another pot, filled with the same earth, he introduced a 

 piece of bread ; in this, all the roots in the immediate vicinity of the 

 mouldering bread died away, and the other roots seemed to have turned 

 off towards the sides of the pot. It is clear that spelt would not grow in a 

 soil copiously mixed with bread ; and if the decaying roots left by a spelt 

 crop have the same effect, it is not difficult to conceive how the decaying 

 remains which a plant leaves in the ground, may injuriously affect its own 

 growth, or that of other plants. (Russell.) 



